1. Field of the Invention
The present invention relates to torque applying devices and, more particularly, is directed to devices for applying a preset torque.
2. Description of the Prior Art
In the mining industry, a bolter is used to drill holes in the roof of a mine and to install roof bolts therein. The bolter includes a wrench that is configured to engage the head of a roof bolt. The wrench is positioned manually on the drill chuck of the bolter and the bolt head is engaged by the wrench. The boom of the bolter is raised and the bolt is thrust against the roof of the mine until the head seats against its bearing plate. The chuck is rotated and the wrench transmits rotational power to the bolt to tighten it in its expansion shell. During tightening, some thrust is maintained on the bolt. The friction associated with the thrust force and the variability of the input torque combine to provide an essentially indeterminate level of torque which is finally applied to the bolt. A need exists for a device which will apply a preset level of torque to bolts.